Authorities: Dontrell Melvin, pictured here at two months old, has been missing for 18 months.

Child protection investigators responded to a neglect case at a Florida home Wednesday night and found only two children where there was supposed to be three.

Hallandale Beach Police officials report that the missing child is 23-month-old Dontrell Melvin, who has not been seen in 18 months. Worse yet, no one has been looking for him -- neither his own parents nor child protection officials. (SEE UPDATE BELOW.)

Father Calvin Melvin Jr., 27, of Hallandale Beach, told police he dropped off his then-5-month-old son with his own parents in July 2011 because of financial trouble. The grandparents, who live in Pompano Beach, told officers they hadn't seen their grandbaby in over a year, according to the Miami Herald.

In the year and a half since Melvin reportedly left the house with the baby and returned without him, Dontrell's mother said she believed her son was with his grandparents.

"What we have is a child that hasn't been seen by the mother or any other relative since July of 2011, and the last person to be in contact with the child is the father," Flournoy said in a news conference. "Our main focus right now is to locate the child. The child may be perfectly safe, but we just need to be confident in that."

Officials have named Melvin as a person of interest. At first the father evaded police but turned himself in Thursday night, reportedly changing his story. Watch the NBC 6 video above.

“He is alleging that he utilized the safe harbor statute in that he dropped his child off at a fire station in Miami Gardens,” Flournoy said, adding "I don't believe it at all."

Police said all children left at fire stations have been accounted for.

Meanwhile DCF placed the remaining two children living with Melvin in the custody of the state, CBS Miami reports. UPDATE: REMAINS FOUND. At a Friday news conference, Flournoy announced human remains have been found at an address provided by Dontrell Melvin's parents.

"We've arrested the mother, Brittney Sierra, and the father after lengthy interviews over the last 12 hours," Flournoy said. "They both have intimated that the child has been harmed in someway by each other, so they are blaming each other as it relates to the child's disappearance."